Biology 2601A/B Lecture Notes - Lecture 13: International System Of Units, Partial Pressure
9 Dec 2015
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Document Summary
It is essential to receive oxygen for metabolism and exchange it with the environment. Along with co2, oxygen is one of the respiratory gases. This has led to the eventual diversification of metazoans, seen most evidently in the. Thus, the rise of oxygen and the diversification of animals are definitely correlated (as animals increase in size, they will require a greater demand of oxygen in the environment). Animals do not actively transport o2 across respiratory surfaces (no pumping of oxygen). Instead, the movement of o2 depends on the rate of diffusion. As all cells need to be bathed in fluid to survive (including moist respiratory surfaces), it is necessary for o2 to first dissolve in liquids and then diffuse across this liquid barrier. The respiratory surface that supplies gas exchange for the entire body of the animal is influenced by three factors: the animal"s size, whether it is terrestrial or aquatic and its metabolic demands (endotherms vs. ectotherms).
